Codeforces 439 A. Devu, the Singer and Churu, the Joker

纯属练习JAVA....

A. Devu, the Singer and Churu, the Joker

time limit per test

1 second

memory limit per test

256 megabytes

input

standard input

output

standard output

Devu is a renowned classical singer. He is invited to many big functions/festivals. Recently he was invited to "All World Classical Singing Festival". Other than Devu, comedian Churu was also invited.

Devu has provided organizers a list of the songs and required time for singing them. He will sing n songs, ith song will take ti minutes exactly.

The Comedian, Churu will crack jokes. All his jokes are of 5 minutes exactly.

People have mainly come to listen Devu. But you know that he needs rest of 10 minutes after each song. On the other hand, Churu being a very active person, doesn't need any rest.

You as one of the organizers should make an optimal sсhedule for the event. For some reasons you must follow the conditions:

• The duration of the event must be no more than d minutes;
• Devu must complete all his songs;
• With satisfying the two previous conditions the number of jokes cracked by Churu should be as many as possible.

If it is not possible to find a way to conduct all the songs of the Devu, output -1. Otherwise find out maximum number of jokes that Churu can crack in the grand event.

Input

The first line contains two space separated integers n, d (1 ≤ n ≤ 100; 1 ≤ d ≤ 10000). The second line contains n space-separated integers: t1, t2, ..., tn (1 ≤ ti ≤ 100).

Output

If there is no way to conduct all the songs of Devu, output -1. Otherwise output the maximum number of jokes that Churu can crack in the grand event.

Sample test(s)

input

3 30
2 2 1

output

5

input

3 20
2 1 1

output

-1

Note

Consider the first example. The duration of the event is 30 minutes. There could be maximum 5 jokes in the following way:

• First Churu cracks a joke in 5 minutes.
• Then Devu performs the first song for 2 minutes.
• Then Churu cracks 2 jokes in 10 minutes.
• Now Devu performs second song for 2 minutes.
• Then Churu cracks 2 jokes in 10 minutes.
• Now finally Devu will perform his last song in 1 minutes.

Total time spent is 5 + 2 + 10 + 2 + 10 + 1 = 30 minutes.

Consider the second example. There is no way of organizing Devu's all songs. Hence the answer is -1.

import java.util.*;

public class Main
{
	public static void main(String[] args)
	{
		Scanner cin=new Scanner(System.in);
		int n=cin.nextInt(),d=cin.nextInt();
		int[] song=new int[n];
		int total=0;
		for(int i=0;i<n;i++)
		{
			song[i]=cin.nextInt();
			total+=song[i];
			total+=10;
		}
		total-=10;
		int ans=0;
		if(total>d)
		{
			ans=-1;
		}
		else
		{
			int left=d-total;
			ans+=left/5;
			ans+=(n-1)*2;
		}
		System.out.println(ans);
	}
}